"Nonlinear dynamics and Chaos" by Steven Strogatz.

It's the only textbook I really read during my university education (sad to admit). Even though I consider it a textbook and not pop-sci, it's incredibly approachable and teaches a framework about dynamical systems which was completely missing from all other courses I took.

Sounds like a humble brag. But it being the only book I managed to read really makes it stick out for me!